Welding apparatus



May 28, 1929. A. R. GROSS WELDING APPARATUS Filed July 2, 1927 6Sheets-Sheet l May 28, 1929. GROSS 1,714.867

WELDING APPARATUS Filed July 1927 6 Sheets-Sheet 2 \r m L m .3

May 28, 1929. A. R. GROSS WELDING APPARATUS Filed July 1927 6Sheets-Sheet 3.

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May 28, 1929.

A. R. GROSS WELDING APPARATUS Filed July 1927 6 Sheets-Sheet QWM NN May28, 1929. A. R. GROSS 1,714,867

WELDING APPARATUS Filed July 1927 6 Sheets-Sheet 6 O n v fi IR I I I I:NNI I I \w I Q Q \I E I III:

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UNITED STATES PATENT OFF ARTHUR R. (moss, or

COMPANY, OF ST. PAUL,

1,714,867 ICE.

ST. PAUL,

MINNESOTA, ASSIGNOR TO GROSS METAL PRODUCTS MINNESOTA, A CORPORATION OFMINNESOTA.

WELDDT G APPARATUS.

Application filed July 2,

My present invention has for its object to provide an improved weldingapparatus intended for general use, but especially adapted for use inthe construction of sheet, metal shells and. more particularly tointernally trus'sed sheet metal doors, and to this end it consists ofthe noveldevices and combinations of devices hereinafter described anddefined in the claims.

In the accompanying drawings,

which illustrate the invention, like characters 'indicate like partsthrougho ut the several views.

Referring to the drawings: Fig. 1' is a view partly in side elevationand showmg a spot welder partly in transverse vertical section and worksupport table having the invention embodied therein and adjusted forextern Fig. 2 is a Fig. 3 is some parts sectioned on 2, on an enlargedscale;

al welding;

plan view of the table; a fragmentary detail view with theline 33 ofFig.

Fig. i is a transverse vertical section taken on the irregular lineenlarged scale;

4'4 of Fig. 2, on' an Fig. 5 is a transverse vertical section taken onthe irregular line 55 of Fig. 2, on an en'- larged scale;

Fig. 6 is a fragmentary detail view principally in section taken on theline 4, on an enlarged scale;

6--6 of Fig.

Fig. 7 is a front elevation with some parts broken ing the away andother parts intermittent feed sectioned showmechanism for the maintraveller on the table; 1

Fig. 8 is a view partly in horizontal section taken approximately on theline 88 of Fig. 7;

Fig. 9 is a side elevation of the automatic control mechanism andswitch;

Fig.10 is a detail view with some parts sectioned on the line 1010 ofFig. 9;

Fig. 11 is an enlarged fragmentary detail view showing the spot welding;

electrodes in position for Fig. 12 is a view corresponding to Fig. 1

with the exception that table are adjusted for i the spot welder andnternal welding;

Fig. 13 is a front elevation of the parts shown in Fig. 12;

Fig. 14 is a detail view principally in section taken on the line 1414of Fig. 12, man

enlarged scale; and

Fig. 15 is a fragmenta in elevation and partly ry detail view partlylongitudinal verto those familiar with parts of the welding 1927. SerialNo. 203,236.

tical section taken on the line 1515 of Fig. 14.

Referring now in detail-to. the drawings,

there is illustrated a door of the'type heretoafter said structure iswelded to the front plate A.

In making the above described door or other sheet metal shell, Ipreferably use a standard welding machine 16 in which the presentinventionis embodied. This welding machine 16 is more or lessdiagrammatically illustrated for the reason that the details andoperation thereof "are well known such machines. How- .to note thefollowing machine, to wit: the upper electrode or-welding point 17,vertically adjustable holder .18, for said electrode, operatingconnections for the holder 18 indicated as an entirety by the numeral19, with the exception of the foot lever 20, spring 21, which normally'yieldingly holds said connections with the electrode 17 and foot lever20 arm 22 in which a. lower elecever, it is essential co-operationtherewith, and an adjustable support 24 for said drop arm 22'.

7 table 26 is placed transversely o the welding machine 16 within thethroat thereof an with the lower electrode 23 extending through anaperture 28 in the top of said table (see Fig. 1)

It will be noted that the back plate B rests .110"

directly on the top of the table 26 and that.

the truss structure C rests on said plate with its corrugationsextending transversely of the welding machine 16, and which corrugationsextend lengthwise of the door. It will also be noted that the \upper endof the electrode 23 is flush with the upper surface of the top of thetable 26 and engages the outer face of the back plate B and that theelectrode 17 extends into the corrugation in the truss structure Coverlying the electrode 23'.

For automatically and successively operating the foot lever to projectthe upper elecv trode 17 and thereby move the same into contact with theunderlying fiat apex D and clamp the bottom plate Band said apex together while they are being spot welded, there is provideda cam 29mounted on a horizontal shaft 30 which extends transversely over thefoot'lever 20 andis journaled on a base-31.

- friction roller 32 on trol switch 25 and close the same, 'eachrotation of said shaft.-

This cam 29 is arranged to engage an antithe foot lever 20, once duringeach rotation of the shaft 30, and hold saidlever depressed against theaction of the spring 21 a predetermined period of time.

' The shaft 30 is driven by an electric motor 33 mounted on the base 31and having a worm 34 on its armature shaft which meshes with a worm gear35 on said shaft. Also keyed to the shaft 30 is a wheel 36 having a cam37 on its periphery arranged'toengage the cononce during It is importantto note that the length of the cam 37 is such that the switch 25 is notclosed until the foot lever 20 has been depressed by the cam 29 to movethe electrode 17 into contact with the truss structure G and that saidswitch is released by said cam before the foot'lever 20 is released bythe cam 29. It will thus be seen that the spot welding is completedwhile the back plate B and truss structure G are held clamped togetherby the electrodes 17 and 23 to prevent arcing.

' plates attached by T-bolts of the corrugation in the -endwisemovement.

Toc'ause the electrodes 17 and 23 to form spot welds in'the door in arow in a given direction and with the weldings spaced predetermineddistances apart, a step by step movement is imparted tothe door in thedirection truss structure C,

there, is provided a main feed mechanism which includes atraveller 38automatically operated from the shaft 30, as will presently appear. Thistraveller 38 is in the form of a channel having inturned side flangesand is mounted in a way 39 set in the topof the table 26 longitudinallyand at the transverse center thereof and supports said traveller withits top flush with the upper face of said table top. For causing thedoor to move on the table top 26 with the traveller 38. there isprovided a pair of short rails 40 in the form of angle 41 to thetraveller 38 and arranged to engage the upper and lower edges of thedoor and hold the same against 'VVhile the T-bolts 41 securely clamp therails 40 120 the traveller 38, this clamping action does not interferewith the free sliding movement of the traveller 38 in the way 39. Thedoor is held between the rails 40 with just enough clearance to permitsaid door to be moved transversely between said rails 40 by a secondarywork feed mechanism, as will presently'appear. The main feed mechanismfurther inelud a cable 42, the intermediate portion of which is wrappedabout a Windlass drum 43 which extends transversely under the table 26,and its ends are extended therefrom in reverse directions over of saidtable, through'the way 39 and attached one to each end of the traveller38. 1 The drum 43 has a shaft 45 journaled in arear bearing guidesheaves-44, on the ends 46 on the under side ofthe table 26 and a. de-

nected thereto by a clutch 49, whereby the windlass drum 43 may bemanually turned to move the traveller 38 and'hence the doorlongitudinally on'the table top and position the same in respect to theelectrodes 17 and 23.

For imparting a step by step rotary movement to the driven shaft 45 fromthedriven shaft 30, there is provided a air of reverselyacting dogs 50arranged or action on a toothed wheel 51. Said toothed Wheel 51 is"keyed to the shaft 45 just back of the bearing plate 47, and the dogs 50are attached by pivot' studs 52 to a pair of radial swinging arms 53pivoted'to the shaft 45 on opposite sides of said wheel and supportsaiddogs for circumferential swinging -movement around the toothed wheel51.- Springs 54, attached to the dogs 50 and anchored to the arms 53,yieldingly hold said dogs foractionon the toothed wheel 51; Forcausingthe dogs 50 to produce a feeding action on the wheel 51, their pivotstuds 52 are extended into apertures 55 in the form of horizontalslotsin a vertically movable slide 56 mounted in ways 57 on the back ofthe bearing plate 47.

Obviously, the slots 55 not only connect the pivot studs 52 to the slide56 but permit'said studs to slide therein during the swinging movementof the arms 53. The slide 56 is moved in one direction and yieldinglyheld raised by a pair of coiled springs 58, the lower ends of which areattached at 59 to said slide and the upper .ends of which are anchoredto a horizontal bar 60 supported from the upper ends of the ways 57.Normally, one of the dogs 50 is held inactive by a dog release. 1 in theform of a ring supported on a plurality of circumferentially spacedflanged wheels 62 loosely journaled on the bearing plate 47 to turnabout. the axis of the shaft 45.

For each dog 50, the dog release 61' is provided with an internaltripping abutment 63 Applied to the outer project-z arranged to beengaged by the active dog 50 during its movementby the slide 56 torotate the toothed Wheel 51 and release said dog after imparting to thewheel 51 a predetermined step of rotary movement. The step of movementimparted to the wheel 51 b the active dog 50 may be varied, at will, byimiting the lifting movement of the slide 56 by the springs 58 andposition the active dog 50 different distances from its trippingabutment 63.

As one means of limiting the lifting movement of the slide 56, the sameis provided with a pair of laterally projecting lugs 64arranged toengage long set screws 65 having threaded engagement with lugs 66 on theways 57. To turn the dog release 61 and thereby render one of the dogs50 inactive and position the respective tripping abutment 63 inoperative relation to the active dog 50, there is journaled on the underside of the table 26 a shaft 67 having a crank arm 68 connected by alink 69 tosaid dog release. A coiled spring 70, anchored to the table 26and attached to the crank arm 68 at its free end, is arranged to movewith said arm from one side of a dead center to the other and therebyyieldingly hold the dog release 61 where set.-

The shaft 67 is journaled in front and rear bearings on the wheel 36,only the former of which is shown, and is in the form of a dependingplate plied to the outer end of the shaft 67 for operating the same. Tolimit the swinging movement of the hand crank 72 and thereby posi tionthe respective tripping abutment 63 in respect to the active dog 50,there is provided a pair-of stoppins 73 on the bearing-plate 71.Obviously, the spring 70, acting on the crank arm 68, holds the handcrank 72 in engagement with one of the pins 73 depending on how the dogrelease 61 is set. A slot 74 is formed in the slide 56 through which theshaft 45 projects to permit free movement of said slide. As previouslystated, the springs 58 operate the slide 56 in one direction and tooperate the same in a reverse direction against the tension of saidsprings, there is keyed to the shaft 30 a crank-acting disc 75eccentrically connected by a cable 76v to said slide andarranged' tooperate thesame once for each rotation of the shaft 30. The cable 76, between the slide 56 and disc 75, runs over guide sheaves 77, only one ofwhich is shown.

The electric feed wires for the motor 33 are indicated by the numeral 78and in one.

thereof is interposed a normally open foot controlled switch 79 mountedon the floor adjacent to the foot lever 20 where the same may be easilyoperated by the operators foot to start the motor 33, and 'whenreleased, said switch willautomatically break the circuit to said motor.

A manually-operated secondary feed mechanism is provided for moving thedoor on the 71. A hand'crank 72 is ap-' which carries the dogs 50 table26 transversely thereof in respect to the electrodes 17 and 23 forpositioning said door for parallel rows of spot' welding between thecorrugations in the truss structure C. This secondary feed mechanismincludes a pair of travellers 80 that are channel-shaped in crosssection, have inturned side flanges, and are slidably supported incorresponding- 1y formed ways 81 set into the top of the table 26transversely of the way 39. The door is held for movement with thetraveller 80 by a pair of rails 82 in the form of angle bars connectedby T-bolts 83 to said traveller. There is sufficient clearance betweenthe door and rails 82 to permit free movement of the door therebetweenby the main feed mechanism. The rails 82 also hold the door forstraightline movement under the action of the main feed mechanism.Spacing washers 84 on the T-bolts 83 holdthe rails 82 with sufiicientclearance to move freely over the top of the table 26. The travellers 80are simultaneously operated by a shaft 85 having a pair of gears 86 thatmesh with racks 87 on the bottoms of said travellers. The shaft 85 ismanually-operated by a hand-piece-equipped wheel 88 on a shaft 89 havinga worm 90 that meshes with a worm gear 91 on the shaft 85.

Theoperation of the weldin apparatus thus far referred to may be brie ydescribed as follows:

The back plate B is first placed on the table 26 lengthwise between therails 40 and crosswise between the rails 82,

and the truss structure C is placed on top of said plate. The rails 40are then adjusted to the ends of the door and the rails82 adjusted tothe longitudinal ed es thereof and secured by the respective -bolts 41and 83, with just suflicient clearance so that the door may be movedtherebetween. The traveller 38 is then adjusted by the hand crank 48 tobring one end of the door at the electrodes 17 and 23 so that nal edgeof the door 1n alignment with the electrodes 17 and 23 toposition thedoor be manually operated at any time either by the hand lever in theconnections 19 or the foot-lever 20.

With the door thus positioned, the operator steps on the switch 79 tostart the motor 33 which drives the shaft 30 in the direction of t earrow marked on Fig. 9. Under the rotion of the shaft 30 itscrank-acting disc 7 5, through the cable connection 76, draws the slide56 downward against the action of the springs 58. This movement of theslide 56 therewith, causes 30, slack is produced mechanism isautomatically and the active dog 50 to rotate the toothed wheel 51 andimpart a step of rotary movement to the shaft 45 to operate the drum 43,and causes the main feed mechanism,including the traveller 38, to imparta step of movement lengthwise to the door on the table 26 to positionthe same for the first spot welding to connect the truss structure C tothe back plate B. During this movement of the slide 56, the activedog 50engages the respective tripping abutment 63 and is moved thereby out ofengagement with the toothed wheel 51 which stops further rotation of theshaft 45. Under further rotation of the shaft 30 and after the door hasbeen positioned as just described, the cam.29 engages the anti-frictionroller-32 on the foot lever 20, and'depresses said lever which lowersthe electrode 17 through the connections 19 heretofore described intoengagement with the respective fiat apex D of the truss structure C andclamp said apex onto the back plate B between the electrodes 17 and 23.Upon further rotation of the shaft 30, the cam 37 closes the switch 25in the circuit for the electrodes 17 and 23 to produce a spot weldingand then releases the electrode 17 before the cam 29 releases the footlever 20 and allows the spring 21 to operate the connections 19 and liftthe electrode 17.

During the latter half rotation of the shaft in the cable 76 by thecrank-acting disc 75, thus allowing the springs 58 to lift the slide 56and reset the active dog 50. A complete rotation of the shaft 45represents one cycle in'the operation of the welding mechanism whichincludes, in timed re-' lation, a step of movement imparted to the doorto position the same in respect to the electrodes 17 and 23, theclamping of the back plate B and truss structure C together by themovement of the upper electrode 17 in respect to the lower electrode 23,to close the switch 25 to complete the circuit for the electrodes 17 and23, and the opening of said switch before the clamping action of theback plate B and truss structure C is released to prevent arcing. Thiscycle produced by the welding (jUCCQSSlVO- h ly repeated in timedrelation as lon as the operator keeps the switch 79 closedand thus 7position the same produces a row of spot welding the full length of thedoor, predetermined distances apart. At the completion of one row ofwelding, the operator releases the switch 79 and operates the hand wheel8810 transversely move the door, as previously described, to

for the next row of welding in the adjacent flat apex I). He also movesthe hand lever 72'to its other extreme Eosition to turn the dog-release(i1 and therey render the active dog 50 inactive and the inactive do 50active, so that the shaft 45 will be 0 erate' in a reverse direction andalso the cor, so that the next row of spot welding will be formedin areverse direction from that just described. This action is repeateduntil the truss structure G is welded to the back plate B at each of itslower flat apexes D.

At the completion of the spot welding of the truss structure G to theback plate B, the

front plate A is positioned on said structure with the plates A and Binterlocked at their longitudinal edges preferably as described inapplication, S. N. 161,630, heretofore referred to.

.To weld the truss structure C to the front 7 plate A requires internalwelding and clamping means that can be inserted into a hollow structure,which in the present instance is between the corrugations in said trussstructure, and said clamping means operated from a distaut point. Toadapt the welding apparatus for this type of work, along horizontalwelding arm or adapter 92 is substitutedfor the electrode 23. Thiswelding arnitif). is adapted to be inserted longitudinally intomnyone ofthe corrugations in the truss structure C from either end of'the door.Said welding arm 92 comprises a tubular rod of electricallyc'onductivematerial suchas copper or bronze, and has applied thereto an insulatingjacket 93. he welding arm 92 extends longitudinally through the throatof the welder and has its inner end anchored at 94 to the frame of saidwelder and insulated therefrom. On the outer or free end of the outerarm 92 is a relatively heavy hollow head 95 of the same material as saidarm and provided with an upstanding welding point or electrode 96aligned with theelectrode 17. By reference to Figs. noted that thewelding head 95 is bf such size and shape that it may be raisedorlowered in the corrugation in the truss structure C .in which .itextends, thereof is such that it will freely move through saidcorrugation without very much lateral movement so that electrode 96 willalways align with the electrode 17. 1 i

To clamp the front plate A to the flat apex D on which it rests, theelectrode 17 is brought into engagement with the outer face of saidplate, as previously described, and there is provided a wedge block 97for lifting the welding head 95 to bring contact with the'inner face ofsaid apex previous to the welding action. The. wedge block 97 slidablyrests on the back plate 13, as a base of resistance, and isautomatically operated from the shaft 30 tolift the welding head 95 andbring its electrode 96 into contact with the respective apex D in thesame timedrelation as that of the electrode 17 with the closing andopening of the switch 25. The welding arm 92 has sufficient flexibilityto permit raising and lowering movements of its electrode 96 and theweight thereof is sufiicient to cause the head 95 to follow the wedgeblock 97 as the same is moved from under said head and 14 and 15, itwill be:

its Welding point 96 into thereb carry the electrode 96 out of contactwith t e respective apex D.

The connections for automatically operating the wedge block 97 in timedrelation with the opening and closing of the switch 25 and the movementsof the electrode 17, as well as the door on the table 26 by the mainfeed mechanisnnincludes an internal cam 98 on the shaft 30. This cam 98is adapted to engage a roller-equipped stud 99 on a bar 100 and draw thesame forward, hold the same a predetermined period of time, and thenrelease the same to be retracted by a coiled spring 101 anchored to thebase of the motor 33. This bar 100 is slidably mounted in a bearing 102on the base 31 and has attached to its rear end a lower horizontaloperating rod 103, connected by a bell-crank 104 to a link 105, which,in turn, is connected by a bell-crank 106' to a rod 107, which extendslongitudinally into the welding arm 92 and its head 95 and has the wedgeblock 97 attached to its outer projecting end. Normally, the spring 101acting on the sliding bar 100 holds the connections 103 and 107,inclusive, with the wedge block 97 in its extreme position from theWelding head 95. The wedge block 97 has a wearing shoe 108 with whichthe welding head 95 has beveled engagement and is further provided witha wearing shoe 109 that rests on the back plate B. The body of the wedgeblock 97 is of suitable material to insulate the shoe 108 from the shoe109. The rod 107 is always out of engagement with the welding arm 92 andits head 95. Q

Suitable means, not shown, will be provided for cooling the welding head95, such as the circulation of water in a tube through the welding arm92 and said head 95.

he operation of the welding apparatus fo the type of work just describedmay be briefly stated as follows:

Normally, the wedge block 97 is positioned to release the welding head95 so that the door may be freely moved by the main feed mechanism. I Atthe completion of the step of movement imparted to the door by the mainfeed mechanism, the cam 98 engages the rollerequipped stud 99, draws thebar 100 forward against the tension of the. spring 101, and through theconnections 103 to 107, inclusive, draws the wedge block 97 under thewelding head 95 and thereby lifts the electrode 96 into contact with theoverlying fiat apex D. At this same time the upper electrode 17 is movedonto the front plate A, as previously de scribed. The cam 98 continuesto hold said connections to the wedge block 97 during the welding actionand does not release said block until after the welding action iscompleted, to prevent arcing.

At the completion of one row of spot welding by the electrodes 17 and96, the main feed mechanism is operated to move the door a sufficientdistance to completely withdraw the electrode 96 and the wedge block 97from the respective corrugation to permit the secondary feed mechanismtobe operated to align the next corrugation with the welding arm 92.

In case the door being welded is of a length greater than that of thewelding arm 92, the welding mechanism is operated to weld the frontplate A to the truss structure C from one end of the door to thelongitudinal center thereof, and then said door is turned end for endand the other half thereof welded in a similar manner. I i

What I claim is 1. In a spot welder, a pair of co-operating electrodes,at least one of which is relatively movable, automatic means forsuccessively causing the electrodes to spot weld a piece of worktherebetween, automatic feed mechanism for positioning the spot weldingon the work in a row and spaced predetermined distances apart, andoffsetting mechanism for causing the electrodes to produce a pluralityof rows of spot welding on the work.

2. In a spot welder, a pair of co-operating electrodes, at least one ofwhich is relatively movable, a normally open control switch in theelectric circuit for the electrodes, intermittent feed mechanism forchanging the relative position of the electrodes and a piece of work tobe spot welded thereby, and automatic mechanism for causing theelectrodes to clamp a piece of work therebetween for closin said switchand then releasing the same uring the period of time in which the workis clamped between the electrodes and for operating said feed mechanismin a cycle of timed relation and for continuously repeating said cycleof timed relation.

3. In a spot welder, a pair of co-operating electrodes, a work supporttable, primary work feed mechanism, automatic means for intermittentlyoperating .the primary feed mechanism in respect to the electrodes toimpart a step by step movement to a piece of work longitudinally on thetable, and secondary feed mechanism for moving said work transversely ofthe table in respect to the electrodes.

4. In a spot welder, a pair of electrodes, a work support table, atraveller mounted in a way on said table having means for holding apiece of work for movement therewith, means for operating the travellerincluding a shaft and connections from the shaft to the traveller, atoothed wheel attached to the shaft, a Spring retracted slide on thetable, a pair of dogs mounted on the slide at diametrically oppositesides of the toothed wheel, yielding means under strain to cause thedogs to engage the toothed wheel, a releasing device for holding eitherone of the dogs inoperative. and automatic means co-operating forprojecting the slide at predetermined time to cause the active dog tointervals of impart a step of movement to the toothed wheel, said devicehaving a cam for releasing the active dog during the projecting movementof the slide.

5. The structure defined in claim 4 in which the dog-releasing device isadjustable to change the position of its cam and thereby vary the lengthof the step of movement imparted to the toothed wheel by the active doThe structure defined in claim 4 in further combination with a crank formoving the dog-releasing'device from one extreme position to the other,and a spring movable with the crank from one side to the other of a dealcenter for holding the crank with the dog-releasing device in either ofits extreme positions.

7. The structure defined in claim 4 in further combination with asecondary traveller mounted in a way on the table for movementtransversely of the main traveller and having adjustable means forholding the work for movement therewith, and means for operating thesecondary traveller.

8. In a spot welder, a air of co-operating electrodes, at least one 0whieh is relatively movable, a normally open control switch in theelectric circuit for the electrodes, a lever for operating the movableelectrode to clamp a piece of work driven member having a cam foractuating the lever to position the movable electrode on the work andthen release the same, and a sec 0nd cam on said member for closin saidswitch and then releasing the same uring the period of time in which thelever is held by the first noted cam.

9. In a spot Welder, 2. pair of relatively movable co-operatingelectrodes, a normally open control switch in the electric circuit forthe electrodes; an operating lever for each electrode, a driven memberhaving a pair of cams for operating said levers to clamp the electrodesonto a piece of work therebetween and then release the same, and anothercam on said member for closing said switch and then releasing the sameduring the period of time in which the levers are held by the firstnoted air of cams.

10. n a welder, eo-operating inner and outer electrodes, means reactingagainst one art of the work and operative to move the inner electrodeagainst another part of the work that is between the electrodes, andmeans for moving the outer electrode against the work.

11. In a welder, a pair of cooperating electrodes, a relatively long armwhich carries one of the electrodes with freedom for move- 4 ment towardand from the other electrode,

means reacting against one part of the work and operative to move theelectrode carried by the arm against another part of the work.

12. In a Welder, co-operating inner and between the electrodes, a

outer electrodes, a relatively long arm on which the inner electrode iscarried for movement toward or from the outer electrode, a projectorreacting against one part of the work and operative to move the innerelectrode against another part of the work that is between theelectrodes, and means for moving the outer electrode against the work.

13. In a welder, co-operating inner and outer electrodes, a relativelylong arm on which the inner electrode is carried for movement therewithtoward or from the outer electrode, and a projector reacting against onepart of the work and operative to move the arm and position the innerelectrode against another part of the work that is between theelectrodes.

14. In a welder, co-ope'rating inner and outer electrodes, a relatively"long arm on which the inner electrode is carried for movement toward orfrom the outer electrode, and a projector reacting against one part ofthe work and operative to move the inner electrode against another partof the work that is between the electrodes and having operatingconnections extending along the arm.

15. In a welder, co-operating inner and outer electrodes, a relativelylong arm on which the inner electrode is carried for movement toward orfrom the outer electrode, a projector reacting against one part of thework and operative to move the inner electrode against -another part ofthe work that is between the electrodes and having operating connectionsextending along the arm, automatic feed mechanism for positioning thespot welding on the work in a row and spaced predetermined distancesapart, and control mechanism for reversing the feed mechanism toalternately change the direction in which the row of spot welding isproduced.

16. In a welder, a pair of co-operating electrodes, a relatively longarm which carries one of the electrodes with freedom for movement towardand from the other electrode, means reacting against one part of thework and operative to move the electrode carried by the arm againstanother part of the work, a work support table, work feed mechanism, andautomatic means for intermittently operating the feed mechanism toimpart a step by step movement to a piece of work on said tablelongitudinally of the arm.

17. In a welder, a work support table, upper and'lower co-operatingelectrodes, a relatively long arm on which the lower electrode iscarried, means reactin against a part of the work on the table andoperative to move the lower electrode against another art of the workthat is between the electro es, and work feed mechanism forintermittently moving the work on the table in respect to theelectrodes.

18. In a spot welder, a

air of co-operating electrodes, at least one 0 which is relativelymovable, a normally open control switch in the electric circuit fortheelectrodes, connections for operating the movable electrode to clampa piece of Work between the electrodes, 5 driving mechanism including acam for ac tuating said connections to position the mow able electrodeon the work and then release ,the same, said mechanism also including asecond cam for closing said switch and then releasing the same duringthe time in which 10 the connections are being acted li-pon by the firstnoted cam.

In testimony whereof I aflix my Signature.

ARTHUR R. GROSS.

